This book explains in clear and vivid language why light plays a central role in life and physical sciences. Fascinating relations arise between physics, chemistry and life sciences from the interaction of light with animate and inanimate matter. Twelve Nobel Prizes have been awarded in the last 30 years for discoveries on these topics including laser techniques, molecular machines, circadian rhythms fluorescent proteins and super-resolution microscopy. Photovoltaics, photocatalysis, photosynthesis, solar hydrogen production, atmospheric ozone production and destruction, DNA sequencing, human vision, and communication in the dark all depend on light absorption and emission. The book concludes with a survey of cultural aspects of light in religion, philosophy and art.